Gear for wheel speed detection and method of manufacturing the same
AssigneeSumitomo Electric Industries, Ltd.
InventorsHiroshi Ueda, Naoki Inui, Yoshinobu Takeda
Life of this patent
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Abstract
A gear for wheel speed detection or sensor ring has a low cost and an excellent corrosion resistance. The sensor ring is mainly made of sintered stainless steel. A surface layer of the sensor ring contains at least 5 atomic % and not more than 25 atomic % of phosphorus, at least 30 atomic % and not more than 70 atomic % of oxygen, and at least 5 atomic % and not more than 50 atomic % of iron, and at least partially consists of an amorphous phase. The surface layer is formed by dipping a sintered stainless steel product in oil at a temperature of 15.degree. to 70.degree. C. containing phosphoric acid groups.
Claims14
A method of manufacturing an article that is mainly made of sintered stainless steel, comprising:
- a) molding a raw material powder;
- b) sintering said molded powder to prepare a sintered stainless steel product;
- and
- c) increasing a corrosion resistance of said sintered stainless steel product by bringing said sintered stainless steel product into contact with an oil mixture, being at a temperature of at least 15.degree. C. and not more than 70.degree. C., and containing phosphoric acid groups, thereby forming on said sintered stainless steel product a surface layer containing at least 5 atomic % and not more than 25 atomic % of phosphorus, at least 30 atomic % and not more than 70 atomic % of oxygen, and at least 5 atomic % and not more than 50 atomic % of iron and at least partially consisting of an amorphous phase.
Dependencies are inferred from the claim text.